NAME

pgmbentley - Bentleyize a portable graymap

SYNOPSIS

pgmbentley [pgmfile]

DESCRIPTION

Reads a portable graymap as input. Performs The Bentley Effect, and
writes a portable graymap as output.
The Bentley Effect is described in "Beyond Photography" by Holzmann,
chapter 4, photo 4. It’s a vertical smearing based on brightness.